They pick anything they can find which is suitable.
When bird find mate they will build a nest
The doctor bird uses silk from the spider web to build their nest.
There is no such bee species.
Birds build their homes out of materials that they find outdoors. Bird's nest are often times built out of dry leaves, sticks, and grass.
The female robin is primarily responsible for building the nest. She uses materials such as twigs, grass, and mud to construct a sturdy structure in which to lay her eggs. The male may help by gathering materials or guarding the nest.
in a tree
That's a bird-so a bird best, if you mean how do they build-specify
penguins don't build nests
Squirrels nest in trees or on the ground, using materials like twigs, leaves, moss, and fur to build their nests.
Yes, some bird species will reuse a nest for their next brood, while others will build a new nest each time.
three
in a palm tree